ZURICH, Jan 7 (Reuters) - Real Madrid's Cristiano Ronaldo said it was incredible that episodes of racism still happen in soccer stadiums after AC Milan abandoned a friendly in Italy last week because of offensive chants by spectators. However, the Portuguese forward was non-committal over Milan midfielder Kevin-Prince Boateng's decision to walk off the pitch over racist insults during the match against lower tier Pro Patria, saying it was a "personal decision."